Circuit for heating thermionic tubes



June'6, 1933. M SNO 1,912,996

CIRCUIT FOR HEATING THERMIONIC TUBES Filed June 15, 1929 INVENTOR MENDEL OSNDS ATTORNEY Patented June 6, 1933 V UNITED STATES PATENT orn g,

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Application filed June 15,1929, Serial No. avinsnand Germany July: 12, 152's, y

This invention is directed to improve ments in circuit arrangements adapted to supply heating energy for thermionic tubes, especially for radio receiving sets, in which a transformer or a choke-coil working with a highly saturated iron core is connected with the alternating current network is used.

to supply the filaments with certain higher harmonics or overtones suited for heating,

whereas the overtones of greater length and the fundamental wave are substantially preelude-d from the filament. It happens that in this scheme, whenever the receiver is used with high amplification, remnants of. the

fundamental wave and overtones of high ed atits middle in order that the frequency.

of the heating potential variations may be doubled in known manner.

One embodiment in which the fundamental idea of the invention is incorporated as shown in the accompanying drawing.

The filament a is supplied with suitable overtones from the secondary winding of a strongly saturated transformer t whose pri mary winding is fed from an alternating current supply line by way of an arrangement precluding or shutting off higher frecland a choke coil cl. ting off the fundamental wave and the undesirable overtones of greater wave length. In parallel relation to the filament a according to the present invention is an inductance g which is grounded in the middle. Its size is so chosen that the undesirable longer waves are substantially deviated (precluded) thereby from the filament, though the waves suited for heating are passed. If for ,rent source frequency suitable for filament quencies and consisting here of a capacity 02 serves for shut-.

heating the filament principally a definite.

overtoneis to be employed, it is recommendable to tune the condenser 02 so as to insure the passage of a maximum value of this wave, while furthermore, in parallel to the inductance g, there is provided another ca pacity 03 which conjointly with g is tuned to this wave.

I claim: a l. In combination a space discharge devlce having an anode, a cathode and a control electrode, a source of alternating curthat it offers a low impedancefor frequencies equal to or less than the frequency of the alternating current from said source and a high impedance for overtones of said ourheating and a connection between the midpoint of said impedance and ground.

2. In combination a space discharge device having an anode, a cathode and a control electrode, a source of alternating ourrent for heating said cathode, a current distortion means connected between said source and said cathode, a grounded impedance connected across said cathode and a tuning element inparallel with saidimpedance for tuning said impedance to an overtone of the frequency of the current from said source.

3. In combination a space discharge device having an anode, a cathode and a control electrode, a source of alternating current for heatingsaid cathode, a current distortion means connected intermediate said source and said cathode, tuning means connected between said source and said distortion means, an impedance connected across said cathode and a connection between the anode of a strongly saturated transformer connected to a source of alternating current and having its secondary connected to said cathode for energizin it, a condenser in series with said secon ary and said cathode forming a circuit tuned to an overtone of the frequency of the current from said source, an inductance connected across said cathode and a connection between the midpoint of said inductance and ground, said inductance be ing adapted to offer a low impedance path to frequencies equal to or lower than the fundamental frequency from said source and a high impedance path for overtones desired to be utilized for energizing said filament. MENDEL OSNOS. 

